Tire building method and rubber strip bonding apparatus

ABSTRACT

The invention can surely accomplish lamination without the generation of voids in building a tire constructed to comprise a plurality of rubber members for a tire when a ribbon-shaped rubber strip (R) is spirally wound and laminated, and uses holding rolls ( 30 ) and two sets of stitching rolls ( 40   a ), ( 40   b ) arranged in parallel with a center of a rubber strip width (W) therebetween to enable performing of an independent pressing motion, such that the rubber strip (R) is pressed and bonded by the holding rolls ( 30 ) in a position, in which the rubber strip (R) is wound, and the stitching roll ( 40   a ) or ( 40   b ) positioned fore in an advancing direction of traverse movement, out of the two sets, is caused to perform a pressing motion in a regional part just after the press whereby a fore part of the rubber strip in the advancing direction is pressed and bonded.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of U.S. patent applicationSer. No. 12/376,089, filed Apr. 3, 2009, and wherein U.S. patentapplication Ser. No. 12/376,089 is a national stage application filedunder 35 USC §371 of International Application No. PCT/JP2006/315682,filed Aug. 8, 2006, the entire contents of which are incorporated hereinby reference.

TECHNICAL FIELD

The present invention relates to a tire building method, in which atleast one rubber member of a tire constructed to comprise a plurality ofrubber members for a tire is built by winding a ribbon-shaped rubberstrip, and an apparatus for bonding a rubber strip.

BACKGROUND ART

Generally, a tire is formed from a plurality of tire constructingmembers. As shown in, for example, FIG. 8, respective parts such as aninner liner 2, a tread 3, side walls 4, and rim strips 5 are formed fromrubber members, which are conformed to characteristics as demanded, andthe rubber members are combined with tire reinforcement members, whichcontain cords such as a carcass layer 6 and a belt layer 7 to constitutea tire T. The reference numeral 8 in the figure denotes a bead portionincluding bead cores 9.

Conventionally, in order to build the respective rubber members,intended rubber members are obtained by performing extrusion throughdies conformed to cross sectional shapes of the respective rubbermembers and then performing cut to predetermined length. A tire is builtby sequentially sticking the rubber members on a building drum. Forexample, an inner liner, a lengthy sheet having a predetermined width iscut to predetermined length to be wound around a cylindrical-shapedbuilding drum and the both ends of the sheet thus cut are joined in onelocation in a circumferential direction.

In recent years, in terms of conformability of a tire to multi-productsmall lot production, assembly accuracy, improvement in productivity,etc., as shown in, for example, JP-A-2002-178415, JP-A-2004-358738,JP-A-2004-216603, and JP-A-2004-216726, respective rubber members suchas an inner liner are formed into predetermined cross sectional shapesby winding an unvulcanized rubber strip, which is extrusion-formed in aribbon configuration, round cylindrical-shaped rotary support body, suchas a building drum, spirally in a tire circumferential direction whileoverlapping a part of the rubber strip.

When the rubber strips are spirally wound and built, in order to pushthe rubber strips, which are continuously supplied, against a peripheralsurface of the rotary support body to bond the rubber strips and air toescape between the rubber strips, a holding roll is ordinarily usedsimultaneously with winding of the rubber strips to sequentially pressthe rubber strips to stick the same (for example, JP-A-2004-216603 andJP-A-2004-216726).

At this time, as shown in FIG. 6, rubber strips R as wound with partialoverlapping are susceptible to variation in a laminated posture 1R at afirst circumference of winding and in a laminated posture 2R at a secondcircumference of winding. Laminated postures at subsequentcircumferences (on and after a third circumference) are the same as thatdescribed above such that postures are varied according to feed pitchesof rubber strips R and cross sectional shapes of rubber strips R, andfore portions in an advancing direction of traverse movement becomeconcave. For rubber strips R, which are varied in posture, a simplycylindrical-shaped holding roll 130 in parallel to a peripheral surfaceof a rotary support body 110 shown in FIG. 7 is difficult to exert apressing force on the whole width of the rubber strips R and so there isa fear that a pressing force on fore, concave portions in the advancingdirection (arrow B) is short to lead to insufficient pressing andremaining voids. Also, depending upon patterns of winding, in the casein which a wind beginning position in winding of plural layers such astwo layers is at positions other than edges of a rubber member of abuilding object, variation in a strip posture in the vicinity of windbeginning is further increased in addition to variation caused by stepsdue to the thickness of the rubber strips in the states described above,so that shortage in pressing force is brought about.

In, for example, JP-A-2004-216603, in addition to an applicator rollincluding a holding roll and serving to supply rubber strips to a rotarysupport body to spirally wind the same for sticking, a stitching roll isprovided in a region just after sticking by the applicator roll to pressand bond edge portions, which form steps due to overlapping of therubber strips, against the rotary support body and squeeze steps formedin the edge portions, and the stitching roll squeezes the edge portionsto eliminate the steps.

With the proposal described above, the stitching roll is fundamentallyprovided to position so that a width center thereof can becomesubstantially the same as that of the applicator roll with a view tosqueezing those steps at the edge portions caused by spiral winding withthe rubber strips partially overlapping, that is, steps at rearward edgeportions in the advancing direction of traverse movement, so that fore,concave portions in the advancing direction of traverse movement are notlocally pressed for variation in laminated posture caused by spiralwinding with partial overlapping. Therefore, there is a fear that foreportions in the advancing direction of traverse movement are not pressedsufficiently and voids are produced. That is, pressing intended forsqueezing voids generated between rubber strips in view of variation inlaminated postures in the advancing direction of traverse movement ofthe rubber strips is difficult.

-   Patent Document 1: JP-A-2002-178415-   Patent Document 2: JP-A-2004-358738-   Patent Document 3: JP-A-2004-216603-   Patent Document 4: JP-A-2004-216726

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The invention has been thought of in order to solve the problem and hasits object to provide a tire building method capable of accomplishing asure and favorable bond without the generation of voids in building atire constructed to comprise a plurality of rubber members for a tirewhen a ribbon-shaped rubber strip continuously supplied from a supplydevice capable of traverse motion relative to a rotary support body iswound, and an apparatus for bonding a rubber strip used in tirebuilding.

Means for Solving the Problems

The invention has a feature in a tire building method of spirallywinding and laminating a ribbon-shaped rubber strip supplied from asupply device, which makes a traverse movement relative to a rotarysupport body for building, on an outer peripheral surface of the rotarysupport body for at least one rubber member of a tire constructed tocomprise a plurality of rubber members for a tire, the method comprisingusing a holding roll arranged to enable pressing a total width of therubber strip and two sets of stitching rolls arranged in parallel foreand aft in a direction of traverse movement with a center of a rubberstrip width therebetween to enable performing of an independent pressingmotion, causing the holding roll to press and bond the rubber strip in aposition, in which the rubber strip is wound round a peripheral surfaceof the rotary support body, and causing the stitching roll positionedfore in an advancing direction of the traverse movement, out of the twosets of stitching rolls, to perform a pressing motion in a regional partjust after the press whereby a fore part of the rubber strip in theadvancing direction is pressed and bonded.

With the tire building method, even in case of either of left and rightspiral windings, the stitching roll positioned fore in the advancingdirection of traverse movement, out of the two sets, is caused toperform a pressing motion whereby a portion, on which press only by theholding roll is made insufficient due to variation in a laminatedposture of the rubber strip, in particular, that portion positioned forein the advancing direction of traverse movement, which is made concavedue to spiral winding accomplished by traverse movement, can be pressedby the stitching roll, so that pressing can be accomplished without thegeneration of shortage in pressing force over a total width of therubber strip and bonding and laminating can be accomplished without thegeneration of voids between the rubber strips.

In the tire building method described above, when the rubber strip iswound in plural layers owing to reciprocation of traverse movement, thestitching roll positioned fore in an advancing direction of respectivereciprocatory traverse movements is used to preferably press respectivefore parts of the rubber strip width in the advancing direction.Thereby, in either of the reciprocatory traverse movements, thestitching roll positioned fore in an advancing direction of traversemovement can surely press a fore part of the rubber strip width.

Further, the invention has a feature in a rubber strip bonding apparatusused in carrying out the tire building method, the bonding apparatusbeing mounted on a rubber strip supply device, which is arranged inopposition to the rotary support body for building, provided to enable atraverse movement relative to the rotary support body, and provided tosupply a ribbon-shaped rubber strip toward the rotary support body, andthe bonding apparatus comprising a holding roll arranged to enablepressing of a total width of the rubber strip in a position, in whichthe rubber strip supplied from the supply device is wound round aperipheral surface of the rotary support body, and two sets of stitchingrolls arranged in parallel fore and aft in a direction of traversemovement with a center of the rubber strip width therebetween to enableperforming of an independent pressing motion in a regional part justafter a position, in which press is made by the holding roll, andwherein the stitching rolls are provided so that the stitching rollpositioned fore in an advancing direction of the traverse movementperforms a pressing motion.

With the bonding apparatus, when spiral winding and laminate building ofa rubber strip is accomplished in traverse movement, that portionpositioned fore in the advancing direction, which is made concave due tospiral winding, can be surely pressed by the stitching roll, so thatpressing can be accomplished without the generation of shortage inpressing force over a total width of the rubber strip and the buildingmethod can be surely carried out.

With the bonding apparatus, preferably, the holding roll and the twosets of stitching rolls, respectively, are arranged on a part of therubber strip supply device to enable performing of an independentpressing motion and move together with a traverse movement of the supplydevice. Thereby, when a rubber strip is wound, there is no need ofadjustment, complex control, and a positioning device to accommodate forvariation in winding pitch, winding pattern, irregularities, etc., sothat only a combination of a holding roll and stitching rolls enablesbonding of a rubber strip and escape of an air.

Also, with the bonding apparatus, the supply device of a ribbon-shapedrubber strip can comprise an extruder for extruding of a rubber materialin a ribbon-shaped configuration, and the holding roll and the stitchingrolls can be provided in the vicinity of a head portion of the extruder.Thereby, while a ribbon-shaped rubber strip having a predetermined crosssectional shape is extruded and supplied from the extruder, the rubberstrip being wound can be wound and built as it is bonded by the holdingroll and the stitching rolls.

With the bonding apparatus, the two sets of stitching rolls can bearranged adjacent to each other in parallel with a center of a rubberstrip width therebetween and provided so that the stitching rollpositioned fore in an advancing direction of traverse movement presses aportion of the rubber strip width positioned fore in the advancingdirection. Thereby, it is possible to surely press apart of the rubberstrip width positioned fore in the advancing direction.

Preferably, outer peripheral surfaces of the two sets of stitching rollsare arcuate in cross section. Thereby, it is possible to surely pressthat portion positioned fore in the advancing direction, which is madeconcave due to spiral winding accomplished by traverse movement, thusenabling bonding so as to eliminate possible voids.

Effect of the Invention

As described above, with the tire building method and the rubber stripbonding apparatus according to the invention, in the case where aribbon-shaped rubber strip is spirally wound and laminated for at leastone rubber member of a tire, the stitching roll positioned fore in theadvancing direction of traverse movement, out of the two sets, is causedto perform a pressing motion whereby a portion, on which press only bythe holding roll is made insufficient due to variation in a laminatedposture of the rubber strip, in particular, that portion positioned forein the advancing direction of traverse movement, which is made concave,can be pressed by the stitching roll, so that bonding can beaccomplished surely and with no voids without the generation of shortagein pressing force over a total width of the rubber strip.

In particular, by arranging two sets of stitching rolls in parallel foreand aft with a width direction center of the rubber strip supplied tothe rotary support body therebetween, there is no need of adjustment,complex control, and a positioning device to accommodate for variationin winding pitch of the rubber strip, winding pattern of the rubberstrip, irregularities, etc., so that only a combination of a holdingroll and stitching rolls enables bonding of a rubber strip and escape ofan air.

BEST MODE FOR CARRYING OUT THE INVENTION

A mode for carrying out the invention will be described below on thebasis of an embodiment shown in the drawings.

FIG. 1 is a schematic, side view showing a state, in which aribbon-shaped rubber strip is wound by a building apparatus, whichcarries out a tire building method according to the invention,

FIG. 2 is a schematic, plan view showing the state, FIG. 3 is aschematic, plan view showing a state of press by a holding roll asviewed in a direction of an arrow A in FIG. 1, FIGS. 4 and 5,respectively, are schematic, plan views showing a state of press by astitching roll as viewed in the direction of the arrow A in FIG. 1, FIG.6 is a cross sectional view showing a posture of winding of rubberstrips, and FIG. 7 is a view illustrating a pressed state by aconventional holding roll.

In the drawings, the reference numeral 10 denotes a rotary support bodyfor building, which is rotatable about a central axis 11, the rotarysupport body comprising a cylindrical-shaped building drum, which isordinarily constructed to enable expanding and contracting. Thereference numeral 20 denotes an extruder arranged in opposition to therotary support body 10 to serve as a device that supplies aribbon-shaped rubber strip R, the extruder being provided so that theribbon-shaped rubber strip R having a predetermined cross sectionalshape conformed to a tire rubber member, such as inner liner, tread,side walls, and rim strip, being an object for building is extruded andsupplied toward the rotary support body 10 from a die 22 provided at atip end of a head portion 21.

The extruder 20 is provided to enable a traverse movement relative tothe rotary support body 10 in an axial direction. Thereby, theribbon-shaped rubber strip R extruded from the extruder 20 iscontinuously supplied to a peripheral surface of the rotary support body10, partially overlapped, wound spirally, and laminated with thetraverse movement and rotation of the rotary support body 10. Traversemovement caused when the rubber strip R is wound includes the case ofmoving the rotary support body 10 in an axial direction, as well as thecase of moving the extruder 20 toward the rotary support body 10 in anaxial direction thereof.

A device that supplies the rubber strip R is not limited to the extruder20 but comprises a supply device that continuously feeds and supplies arubber strip, which is extruded and fed in a separate process.

A bonding apparatus used in winding and building the rubber stripsupplied in the manner described above has the following construction.

The reference numeral 30 denotes a set of holding rolls supported by asupport bracket 23 connected and fixed to the head portion 21 of theextruder 20 as a device that supplies the rubber strip, and arranged toenable pressing of the rubber strip R extruded and supplied from theextruder 20. The holding rolls 30 are arranged so thatcylindrical-shaped roll bodies 31 made of an elastic body, such asrubber and polyurethane, having an elasticity suited to press arejournaled in parallel to a peripheral surface of the rotary support body10, supported to be advanced to and retreated from the peripheralsurface of the rotary support body 10 by an actuator 33, such as aircylinder, mounted (depiction of mount means is omitted) to the supportbracket 23, and perform an advancing motion at the time of winding ofthe rubber strip R to thereby press the rubber strip R in a position, inwhich the rubber strip R is wound. In particular, the roll bodies 31have a larger, axial width than a width of the rubber strip R extrudedfrom the die 22 of the extruder 20 as viewed in plan view and arearranged in positions conformed to the rubber strip R so as to enablepressing of a total width of the rubber strip R. The reference numeral35 in the figure denotes journal members of the roll bodies 31.

The reference numerals 40 a, 40 b denote two sets of stitching rollsarranged to press the rubber strip R in a regional part just after aposition, in which press is made by the holding rolls 30, the respectivestitching rolls being arranged in parallel fore and aft in the advancingdirection of the traverse movement with a center C width direction ofthe rubber strip R extruded and supplied toward the peripheral surfaceof the rotary support body 10 from the die 22 of the extruder 20therebetween. In particular, as shown in the figure, the two sets ofstitching rolls 40 a, 40 b are supported so that respective roll bodies41, 41 are arranged adjacent to each other in parallel with the widthdirection center C therebetween to be rotatably journaled by the journalmembers 45, 45 and caused by actuators 43, 43, such as air cylinder,mounted (depiction of mount means is omitted) to the support bracket 23,to perform a pressing motion independently, the roll bodies beingprovided to press a fore part of the rubber strip R wound round andlaminated on the rotary support body 10, preferably, a range of ¼ to ½times a rubber strip width W from an edge in the advancing direction oftraverse movement owing to the pressing motion of the stitching roll 40a or 40 b positioned fore in the advancing direction.

In terms of escape of an air by press and an effect of bond, outerperipheral surfaces of the respective roll bodies 41, 41 of thestitching roll 40 a or 40 b are preferably arcuate in cross section, andin particular, spherical in shape like a blastomere formed by cuttingboth sides of a spherical body. Also, the stitching rolls 40 a, 40 bpreferably have a larger width than ½ the rubber strip width W, forexample, a substantially the same width as the rubber strip width W asshown in the figure. Of course, a smaller width than the width can alsobe used depending upon the cross sectional shape of the rubber strip R.

The roll bodies 41, 41 of the stitching rolls 40 a, 40 b are preferablymade of an elastic body, such as rubber and polyurethane, having amoderate elasticity like the holding rolls 30. Further, it is possibleto use metallic rolls.

With the building apparatus provided with the bonding apparatusconstructed in the manner described above, for at least one of rubbermembers constituting a tire, when a ribbon-shaped rubber strip Rextruded from the extruder 20 as a supply device is spirally wound andlaminated owing to rotation of the rotary support body 10 and relativetraverse movement of the extruder 20 relative to the rotary support body10, the rubber strip R is pressed and bonded by the holding rolls 30 ina position, in which the rubber strip R is wound round the peripheralsurface of the rotary support body 10, that is, in a position, in whichthe rubber strip R extruded from the extruder 20 abuts against therotary support body 10 to begin to be wound (FIG. 3). At this time, theholding rolls 30 press convex portions formed by overlap of the rubberstrip R, a part of which overlaps and is wound.

In case of either of left and right spiral windings, the stitching roll40 a or 40 b positioned fore in the advancing direction of traversemovement, for example, the stitching roll 40 a out of the two sets ofstitching rolls 40 a, 40 b is caused in the regional part just afterpress to perform a pressing motion whereby a fore part of the rubberstrip R in the advancing direction (a direction of an arrow B in thefigure) is pressed and bonded. In the case where the advancing directionof traverse movement is opposite to that described above, the stitchingroll 40 b positioned fore in the advancing direction is caused toperform a pressing motion whereby a fore part in the advancing directionis pressed and bonded in the manner described above.

Thereby, a portion, on which a pressing force only by the holding rolls30 is made insufficient due to variation in a laminated posture of therubber strip R, in particular, that portion positioned fore in theadvancing direction, which is made concave due to spiral windingaccomplished by traverse movement, can be surely pressed by thestitching roll 40 a or 40 b, so that a sufficient bond can beaccomplished so as to eliminate possible voids generated between therubber strip R and the rubber strip R.

Also, as shown in FIG. 5, in winding the rubber strip R in plural layersowing to reciprocation of traverse movement with a width directioncenter of the rotary support body 10 as a wind beginning position of therubber strip R, the stitching roll 40 a positioned fore in the advancingdirection B is caused in the same manner as that in FIG. 4 to perform apressing motion when the traverse movement goes from a center to an edgeportion, and the stitching roll 40 b positioned fore in the advancingdirection opposed to that described above is caused in the same manneras that in FIG. 5 to perform a pressing motion when the traversemovement returns after it turns back at the edge portion. Thereby, ineither of a first layer and a second layer made by spiral windingaccomplished by traverse movement, it is possible to readily conform tovariation in a laminated posture as well as to a step in a windbeginning position and to use the stitching roll 40 a or 40 b to surelypress that portion positioned fore in the advancing direction, which ismade concave due to spiral winding. Therefore, in case of winding ofplural layers, bonding and winding lamination can be made so as toeliminate possible voids generated between the rubber strip R and therubber strip R.

In addition, while the embodiment described above has been describedwith respect to the case where a ribbon-shaped rubber strip R beingspirally wound and laminated is spirally wound round and laminated onthe cylindrical-shaped building drum as the rotary support body 10, arotary support body includes one formed by winding and laminating acarcass layer or a belt layer or other rubber layers as a base layer onthe building drum and so the rubber strip can be wound round andlaminated on the base layer in the same manner as that described above.Further, also in the case where, for example, a side wall or the like iswound round and laminated on a cylindrical-shaped band case or a greentire, which undergoes shaping deformation, the embodiment can be carriedout with the band case or the green tire as a rotary support body in thesame manner as that described above. Also, the embodiment can be carriedout also in the case where a conventional extruded member and a rubberstrip member are combined to laminated a predetermined rubber member. Atthis time, in pressing a conventional extruded member having athickness, two sets of stitching rolls of the bonding apparatus can becaused to perform a pressing motion simultaneously.

INDUSTRIAL APPLICABILITY

The invention can be preferably made use of in a tire building method,in which at least one rubber member of a tire constructed to comprise aplurality of rubber members for a tire is built by spirally winding andlaminating a ribbon-shaped rubber strip supplied from a supply device,which makes traverse movement relative to a rotary support body forbuilding, on an outer peripheral surface of the rotary support body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic, side view showing a state, in which aribbon-shaped rubber strip is wound by a building apparatus, whichcarries out a tire building method according to the invention.

FIG. 2 is a schematic, plan view showing the state.

FIG. 3 is a schematic, plan view showing a state of press by a holdingroll as viewed in a direction of an arrow A in FIG. 1.

FIG. 4 is a schematic, plan view showing a state of press by a stitchingroll as viewed in the direction of the arrow A in FIG. 1.

FIG. 5 is a schematic, plan view showing a state of press by a stitchingroll as viewed in the direction of the arrow A in FIG. 1.

FIG. 6 is a cross sectional view showing a posture of winding of rubberstrips.

FIG. 7 is a view illustrating a pressed state by a conventional holdingroll.

FIG. 8 is a cross sectional view illustrating a tire structure.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

10: rotary support body, 11: central axis, 20: extruder, 21: headportion, 22: die, 23: support bracket, 30: holding roll, 31: roll body,33: actuator, 35: journal member, 40 a, 40 b: stitching roll, 41: rollbody, 43: actuator, 45: journal member, A: direction, B: advancingdirection of traverse movement, C: width direction center, R: rubberstrip

The invention claimed is:
 1. A rubber strip bonding apparatus,comprising: rotary support body to which a ribbon-shaped rubber strip isspirally wound and laminated on an outer peripheral surface of therotary support body, for at least one rubber member of a tireconstructed to comprise a plurality of rubber members for a tire; arubber strip supply device, which is arranged in opposition to therotary support body for building, provided to enable a traversingmovement in an axial direction relative to the rotary support body, andprovided to supply the ribbon-shaped rubber strip toward the rotarysupport body; and a bonding apparatus mounted to the rubber strip supplydevice, the bonding apparatus comprising: a support device connected tothe rubber strip supply device, a holding roll supported by the supportdevice and having a width to enable pressing of a total width of theribbon-shaped rubber strip in a position, in which the ribbon-shapedrubber strip supplied from the supply device is spirally wound around aperipheral surface of the rotary support body, a pair of actuatorsmounted to the support device, and a pair of stitching rolls operativelyconnected to respective actuators via respective journal members thatrotatably journal the pair of stitching rolls, the pair of stitchingrolls being respectively disposed in parallel fore and aft in adirection of traversing movement, wherein the pair of actuatorsrespectively actuate the pair of stitching rolls to enable the repectivestitching rolls to independently perform a pressing motion, wherein thepair of stitching rolls are supported with respect to the rubber stripsupply device so that respective roll bodies of the stitching rolls arearranged in parallel and so that a width direction center of theribbon-shaped rubber strip supplied from the rubber strip supply deviceis positioned between said pair of stitching rolls, and wherein the pairof stitching rolls are arranged with respect to the rubber strip supplydevice so that when the rubber strip supply device makes the traversingmovement relative to the rotary support body, the stitching rollpositioned fore in an advancing direction of the traversing movementindependently presses substantially a half part of the ribbon-shapedrubber strip to bond the ribbon-shaped rubber strip, and the stitchingroll that is positioned aft in the advancing direction does not pressthe ribbon-shaped rubber strip.
 2. The rubber strip bonding apparatusaccording to claim 1, wherein the rubber strip supply device of theribbon-shaped rubber strip comprises an extruder for extruding of arubber material in a ribbon-shaped configuration, and the holding rolland the pair of stitching rolls are provided in the vicinity of a headportion of the extruder, and wherein the extruder is arranged so as tobe able to supply the ribbon-shaped rubber strip directly to the rotarysupport body.
 3. The rubber strip bonding apparatus according to claim1, wherein outer peripheral surfaces of the pair of stitching rolls arearcuate in cross section.
 4. The rubber strip bonding apparatusaccording to claim 1, wherein the respective stitching rolls have alarger width than ½ a width of the ribbon-shaped rubber strip.